Circuit interrupter



' June 6, 1933.

A; c. CRAGO 1,912,932

C IRCUI '1 INTERRUPTER Filed Aug. 29, 1927 F195 Fly 4. F1915. F1916; my.7.

HP uu- INVENTOR fllan a myqdeceased' @Samuel D. Crago, AdministratorATTORNEY Patented June 6, 1933 v UNITED STATES PATENT OFFICE ALAN C.CRAGO, DECEASED, LATE 0F IPITTSBURGH, PENNSYLVANIA, BY SAMUEL D. CRAGO,ADMINISTRATOR, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WE$T INGHOUSEELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIACIRCUIT INTERRUPTER Application filed August 29, 1927. Serial No.216,033.

The invention relates-to circuit interrupters and particularly tocircuit interrupters which accomplish their purpose by forcing the arcincident to the opening. of their contacts into a deionizing chamber,comprising means, such as a pluralityof superposed metallic plates,which enables them to. interrupt currents of large power.

While the invention is here shown as embodied in a circuit interrupterfor alternating-current service and while particularly effective in suchservice, many of the principlcs of my invention are equally applicableto circuit interrupters for direct-current circuits.

One object of the invention is to provide means to assist in theextinguishing of the arc incident to the opening of the contacts of acircuit breaker by connecting a plurality of resistance elements inshunt and in series to the said are, thereby facilitating itsextinction.

Another object to the invention is to provide an arrangement whereinasingle deionizing chamber is used with'a plurality of resistanceelements to successively extinguish the arcs incident to their use ininterrupting a circuit in the manner above described.

A further object of the invention is to pro vide a. means wherein asingle deionizing chamber is used to interrupt the flow of energy in anelectric circuit in several successive ste s or stages.

ther objects of the invention will become apparent through reading thefollowing specification taken in connection with the drawing in which:

Figure 1 is a side view of a circuit interru ter embodying theinvention,

ig. 2 is a detail view of a deionizing me-' tallic late embodied in thedeionizing chamher 0 one form which may be utilized in connection withthe invention, and

Figs. 3 to 7, inclusive, are illustrative diagrams showing the circuitconnections of the resistance elements at various points in the courseof operation of the circuit breaker.

Patent No. 1,784,760 and No. 1,819,207 issued, respectively, on December9, 1930 and August 18, 1931, show arrangements in which the arc incidentto the opening of circuit breakers in air is forced into a deionizingchamber and therein extinguished at the zero pointof an alternating-current wave. Bythe employment of such cleion-izing chambers, it ispossible to' interrupt currents of large value in circuits of highvoltage which hitherto have only been broken by the use of oil or otherarc-qucnching mediums. In connection with the extinguishing of arcs andsuch deionizing structures, ithas been found that the amount of currentwhich can be interrupted may be increased it resistances of suitablevalues are connected in shunt to the contacts when they first open andare later connected in series therewith. The arc is so to speak,interrupted in two or more stages instead of at a single stroke.

It has also been found desirable to interrupt such an arc in more thantwo stages by providing a plurality of resistance sections of difl erentvalues. The section of smallest resistance is connected in shunt to thearcing contacts when they first open and acts to assist the de-ionizingchamber in extinguishing the arc. It would be possible to furnish adeionizing chamber for each section of resistance used in extinguishingthe are but,

since the structure of such chambers is rela tively expensive, it isseen that expense may be saved through an arrangement in which a singledeionizing chamber coacts with the first section of resistance toextinguish the arc in shunt thereto, and is then switched to extinguishthe arc in the second resistor section; and so on, for all the resistorsections used.

A specific arrangement by means of which it is here proposed toaccomplish this general result shows a. circuit breaker comprising maincontacts 1 and 2 and a bridging member 3 of conventional type. breakeris actuated to its open position, the arm 4 supporting the bridge member3 moves about its hinge 5 to the right, separating the bridging member 3from the main contacts. It is usually desirable to provide, in additionto the bridging member 3, an arcing contact 6 which breaks its contactlater than the When the circuit I main contactor. Such auxiliarycontacts are well known in the art.

The upper end of the arm 4 supports an arcuate member 7 faced with asuitable insulator 8 upon which are positioned, at intervals, a seriesof metallic blocks. 9, 10, 11 and12. The contact blocks are connected byany suitable means, such as flexible connectors 13, to a variableresistor 14 of any suitable type. The upper faces of the blocks '9, 10,11 and, 12 are machined to be concentric with the hinge 5. Above thesingle arm 4 is positioned, the deionizing chamber 15 which comprises apair of metallic endplates 16 and 17 faced on each side by insulatingplates to form an 'inclosure which is open at the top: This chamber has,at its bottom end, a pair of arcing horns 18 and 19, the first mentionedof which may be referred to as a principalcontact against the lowerfaces of which the contact blocks 9, 10, 11 and 12, aforesaid, make amoving engagement. The lower part of the deionlzmg chamber*15 is emptybut in its upper portion are located a series'o-f spaced verticalmetallic plates of the form shown in detail in Fig. 7. The plates may beof copper, of an inch thick and spaced apart of an inch by a series'ofwashers of fish paper or other suitable insulation. The lower edges ofthe metallic plates are provided with notches of substantially'V-shape,as shown in Fig. 2, which aline when the plates are assembled in thedeionizing chamber to form a V-shaped groove which greatly increases theefliciency of the chamber in extinguishing arcs.

The lower portions of the insulating slde plates of the deionizingchamber above mentioned are held tightly between the poles of a blowoutmagnet 21 comprising an iron yoke 22 and an exciting winding 23therefor. One end of the blowout-magnet winding is connected to thecontact terminal 1 and the other end is connected to one of the endplates 16; The other end plate 16 is connected,

\ through arm 4 and conductor 25, to the other main contact 2. Aninspection of the drawing will show that the blowout magnet and thedeionizing chamber 15 are thereby connected in series across the maincontacts 1 and'2.

The deionizing chamber above described is not part of the presentinvention but forms the subject matter of the Slepian Patent 1,784,760above mentioned. Such being the general structure of the present circuitbreaker, its mode of operation in opening the circuit will now bedescribed.

When the main bridging member 3 and the auxiliary contact 6 open thecircuit between the main contacts 1 and 2, contact member 9 is sopositioned as to bridge the arcing horns 19 and 18. The opening of thebridge across members 1 and 2, however, forces current to flow throughthe winding 23 of the blowout magnet to the end plate 16 and thenthrough the arcing horn 18, contact member 9, arm 4 and conductor 25 tothe other contact 2. Fig. 3 diagrammatically illustrates this stage ofoperation.

A slight additional movement of the arm 4 breaks contact between theblock 9 and the arcing horn 18 and draws an arc therebetween. This areis shunted by the first section 27 of the resistor 14, since the contactblock 10 is so positioned that it makes contact with the arcing horn 18.A further movement of the arm 4 to the right, transfers the right-handterminal of the are from the member 9' to the other arcing horn 19. Theblowout magnet 21 then drives this are upward into the deionizingstructure comprising the superposed plates and forces it into theV-shaped groove therein. As the current in this are falls to zero in thecourse of the alternating-current cycle the arc path is rapidlydeionized because of the contiguity of the metallic plates which tend todischarge any ions which may impinge upon them. lVhen, in the course ofthe succeeding alternating-current wave, the voltage between the endplates 16 rises, what few ions remain free in the arc path are drawninto contact with the deionizing plates and are discharged also. Inconsequence, the electric force is insuflicient to reestablish anappreciative flow of current through the arc path, and the arc remainsextinct after the end of the first half cycle of the alternatingcurrent. Fig. 4 represents this operative position of my interrupter.The foregoing steps, however, leave a certain amount of current flowingthrough the resistor section 27. A further movement ofthe arm 4 to theright breaks contact between the contact block 10 and the arc horn 18and establishes an arc therebetween shunted by the resistor section 28.This process,

it will be seen, is precisely like that whichoccurred on the breakingcontact of contact section 27 is now in series with the main circuit. Asa. consequence of this later condition, the value to which the currentcan rise in she alternating half wave is strictly limite A furthermovement of the arm 4 transfers the arc to the other arcing horn 19, andthe blowout magnet 22 forces it up into the deionizing structure whereit is extinguished I in its turn. Fig. 5 represents the circuitconnections at this stage of the operation. A further movement of thearm 4 then breaks contact between the block 11 and the arc horn 18,shunting the arc therebetween by the resistor section 29 and placingresistor sections 27 and 28 in series with the main line to furtherlimit the rise of current, as shown diagrammatically in Fig. 6. The arebetween members 18 and 11 ishrtinguished precisely in the manner whichhas been described be fore and, finally, are from the arc horn 18, whichis shunted by no resistance, but which is so limited by the resistorsections 27, 28 and 29, which are now connected in series with the mainline, as indicated in Fig. 7, that the deionizing structure is capableof completely interrupting current flow in the circuit.

Accordingly, there has been provided means by which a single deionizinchamber can be made to interrupt the arc ormed by insertion of aplurality of resistance sections in series with a circuit in which it isdescribed to interrupt current flow, thereby making possible theinterruption of larger amounts of power than would be possible were thecircuit to be interrupted at a single operation.

While the present invention has been described as used in connectionwith specific devices, it will be obviousthat it is not limited to suchuse but is of general applicaitonto eii'ect circuit interruption evenwhen special means are provided to extinguish the arcs incident toseparation of the contacts.

The principles which are embodied in the circuit breaker hereindescribed are applicable to, and may be utilized for, many other Iprocesses which will be apparent to those skilled in the art withoutdeparture from the scope of the invention. Accordingly, it is desiredthat the claims herein shall be given the broadest interpretationconsistent with the limitations expressed therein and with those imposedby prior art.

What is claimed is:

1. In a circuit interrupter a principal contact, a movable contactadapted to draw an are from said principal contact and to connect animpedance in shunt to said arc, means to transfer a terminal of said arefrom said movable contact to an electrode contiguous to means toextinguish said arc, means to remove said movable contact from thevicinity of said are extinguishing means, a second movable contactadapted to draw an arc in series with said impedance from said principalcontact and in contiguit-y to said are extinguishing means.

2. In a circuit interrupter, a pair of arc terminal members, means toestablish an are, means for transferring said are to said pair of arcterminal members. means for connecting a resistance in shunt with saidarc. means for drawing a second arc in series with said resistance andmeans for transferring said second are to said pair of arc terminalmembers.

3. In a circuit interrupter, means for deionizing an are including apair, of arc terminal members, separable contacts for drawing an are,means for transferring said are to said pair of arc terminal members,means for connecting a resistance in shunt with said are. means f rdrawing a second arcin series a contact block 12 draws an with saidresistance and means for transferring said second arc to said pair ofarc terminal members,

4. In a circuit interrupter, means for drawing an are, means forshunting said are by a resistance, means for deionizing an arc includinga pair of arc terminal members,

means for transferring said are from said are drawing means to saidterminal members, and means for drawing a second are after theextinction of said first arc, means for shunting said second arc with ahigher resistance than said first arc, and means for transferring saidsecond arc to said pair of arc terminal members to be extinguished bysaid deionizing means.

5. In a circuit interrupter, means for drawing an are, means forshunting said are by a resistance, means for deionizing an arc including a pair of arc terminal members, means for transferring said arcfrom said arc drawing means to said terminal members, and means fordrawing a second are after the extinction of said first arc and inseries with said resistance, and means for transferring said second arcto said pair of arc terminal members to be extinguished by saiddeionizing means.

6. In a circuit interrupter, means for drawing an are, means forshunting said are by a resistance, means for deionizing an arc includinga pair of arc terminal members, means for transferring said are fromsaid arc draw- 1ng means to said terminal members, and means for drawinga second are after the extinction of said first arc, said second arebeing drawn in shunt with a resistance higher than that across saidfirst arc, and in series with a current limiting resistance, and meansfor transferring said second arc to said air of arc terminal members tobe extinguis ied by said deionizingmeans.

7. In a circuit interrupter, means for drawing an arc, means forshunting said are by a resistance, means for deionizing an arc includinga pair of arc terminal members, means for transferring said are fromsaid are drawing means to said terminal members, and means for drawing asecond arc after the extinction of said first arc, means for shuntingsaid second arc with a higher resistance than said first are, means fortransferring said second arc to said pair of arc terminal members to beextinguished by said deionizing means, and means for moving both of saidarcs on said terminal members.

8. In a circuit interrupter,a pair of arc terminal members, a principalcontact connected to one of said are terminal members, a movable contactfor drawing an are from said principal contact and making contact withthe other of said are terminal members to transfer the are thereto, asecond movable contact for drawing another are from said principalcontact and making contact with said other arc terminal member totransfer the are thereto, said movable contacts having a resistanceconnected therehet-Ween.

9. In a circuit interrupter, a pair of arc terminal members, a principalcontact connected to one of said are terminal members, a plurality ofmovable contacts, means for moving said contacts from said principalcontact to draw a series of arcs therefrom and to malie contact with theother of said are terminai members and transfer said arcs thereto, saidmovable contacts having resistances connected therehetween so as toshunt each of the arcs as they are drawn.

10. In a circuit interrupter, a pair of are terminal members, aprincipal contact connected to one of said are terminal member", aplurality of movable contacts, means for moving said contacts from saidprincipal contact to draw series of arcs therefrom and to make contactwith the other of said are termi-- nal members and transfer said arcsthereto, said movable contacts having resistances connected therebetweenso as to shunt each of the arcs as they are drawn, each of saidresistances having a higher value than the resistance shunting thepreceding pair of contacts,

11. In a circuit interrupter, a pair of arc terminal members, aprincipal contact connected to one of said are terminal members, aplurality of movable contacts, means for moving said contacts from saidprincipal contact to draw a series of arcs therefrom and to make contactwith the other of said are terminal members and transfer said arcsthereto, said movable contacts having resistances connect-- edtherebetween so as to shunt each of the arcs as they are drawn and to bein series with the arcs drawn by the following movable contacts, each ofsaid resistances havinga higher value than the resistance shunting thepreceding pair of contacts.

In testimony whereof, I have hereunto suhscribed my name this 18th dayof August,

SAMUEL D, CRAGO, Administrator of the Estate of Aizm (7.

OM90, Deceased,

